Rapid prototyping has been drawing attention as a method for precisely producing molded articles including a three-dimensional curved surface at high speed. Specifically, the method is that a three-dimensional structure is sliced at constant intervals in the height direction, each obtained cross section is analyzed to collect information, and the cross sectional information is laminated to reconstruct the three-dimensional structure. Rapid prototyping is classified into some methods depending on the molding method. Examples of the method include optical molding method, paper lamination method, powder sintering method, and powder-layered manufacturing method (powder adhesion method). Among them, the powder-layered manufacturing method is expected to be put into practical use because it can be performed with a convenient apparatus such as an inkjet printer and molding can be performed at relatively high speed.
The powder-layered manufacturing method (powder adhesion method) is a method for obtaining, as a molded body, a laminated body that is obtained by repeating a step of flatly spreading a powder layer to form a powder layer and a step of spraying a spray solution onto a predetermined area in the powder layer.
For such powder-layered manufacturing method, some methods have been proposed until now. For example, there is a method for forming an artifact. The method includes: applying, to a first area in a first layer of nonadhesive particles each having an activatable adhesive, a liquid for activating the adhesive in an amount sufficient to activate the adhesive to the extent that the particles in the first area adhere to each other to form an essentially solid single first cross section area that is surrounded by the nonadhesive particles; forming a second layer of the particles on the first layer; and applying, to a first area in the second layer of the particles, the liquid in an amount sufficient to activate the adhesive to the extent that the particles in the first area in the second layer adhere to each other and to at least a part of the first area in the first layer for adhering to the first cross section area and for forming a second cross section area that is surrounded by the nonadhesive particles. In the method, at least a portion of the particles have poor solubility in the liquid, and the first cross section area forms, together with the second cross section area, an essentially solid single article (Patent Document 1).
Furthermore, the inventors of the present invention have developed and applied a method for producing a pattern. The method includes: a step (a) of planar spreading, on a table, a mixed powder containing a water-soluble inorganic salt and a water-soluble organic polymer component, and then selectively spraying, onto the mixed powder layer, a spray liquid containing at least one selected from a water-miscible organic solvent and water through a nozzle to make the binding strength among the mixed powder particles in the sprayed area higher than that among the mixed powder particles in the unsprayed area; a step (b) of further spreading the mixed powder on the mixed powder layer after the spray, and then selectively spraying the spray liquid through a nozzle onto the mixed powder layer; a step (c) of repeating the step (b) twice or more times to form a pattern having a shape from the sprayed areas; and a step (d) of removing the pattern from the powder (Patent Document 2).